Development of a gallic acid based time temperature indicator with adjustable activation energy

A time temperature indicator (TTI) is an intelligent packaging device that can monitor and reveal food quality loss through visualized information. In this study, a new TTI mechanism was demonstrated based on the nonenzymatic browning reaction of gallic acid (GA), a nontoxic, low-cost ingredient. The influence of pH condition (pH 8.0–6.0) on the chemical kinetics and coloring process of the GA aqueous solution (20 mM) was investigated. The coloring reaction was easily observable with the naked eye, exhibiting kinetics suitable for visualizing temperature's impact on food storage and transportation. The pH-dependent activation energies (Ea) of the proposed TTI ranged from 17.57 kJ/mol (at pH 8.0) to 70.36 kJ/mol (at pH 6.0). The milk quality model was also established through titratable acidity analysis, and the Ea was calculated to be 51.68 kJ/mol, correspond to the GA TTI with a pH of 6.5.